The present invention relates to web cleaners in general and more specifically, to a treatment system that lifts debris from the surface of a web of substrate material without touching either of its upper and lower surfaces.
Previously, many types of web cleaners have been used to provide an effective means for removing unwanted particles from the surface of a web in the printing discipline. A number of approaches have been used with limited or little success. Bristles, in the form of a brush rotating at a speed of 600 to 800 rpm, have been employed to lightly brush the surface of the web. Compressed air has been somewhat successful, however it was found that almost 2 pounds per square inch of pressure was required, which required considerable energy and had other complications. The combination of a rotating brush and vacuum was considered to be a viable solution, however it was also complicated and required vacuum blowers at high volume and brushes that contacted the surface of the web.
A search of the prior art did not disclose any patents that possess the novelty of the instant invention, however the following U.S. patents are considered related:
Wieloch, et al. in U.S. Pat. No. 6,162,303 teaches a process for cleaning a web having surfaces on opposite sides of the web with a cleaner roller against a major surface in one direction while the transport of the web remains uninterrupted and rolling the contact cleaner roll against the major surface in an opposite direction while the transport of the web is uninterrupted.
U.S. Pat. No. 6,178,589 issued to Kaim is for a track assembly that permits a pair of cleaning devices to operate on either side of a paper web moving upward through the floor of a press. The track assembly facilitates mounting and rapid removal of web cleaning buffs from beneath a press.
Baum in U.S. Pat. No. 6,193,810 discloses a method of cleaning tissue webs in a in rewinder utilizing the Coanda effect with a thin layer of air that scrubs off dust and lint imbedded and entangled in the web surface while stabilizing the web in its travel.
Ziegelmuller, et al. in U.S. Pat. No. 6,195,527 teaches a web cleaning device with a nesting structure that supports a coil of web fabric. A lip member forms a part of the nesting structure and a pay out end of the coil is wrapped around the lip member with a take up spindle spaced from the coil.
U.S. Pat. No. 6,207,227 issued to Russo; et al. presents a cleaning sheet with tacky surface coating that cleans feed rollers
U.S. Pat. No. 6,259,882 of Lindblad, et al is for removing electrostatically charged particles from a surface of an image bearing belt.
In the printing discipline which includes lithographic offset printing, flexographic printing, gravure printing, letterpress printing and the like, blanket piling is a source of wasted time and lost production due to the necessity of frequent blanket washes. Lint, paper fibers and coating on the surface of the substrate can cause halftone plugging and so called xe2x80x9chickeysxe2x80x9d, which requires removal and washing of the blanket. Frequent blanket washes shorten the blanket""s life and place unnecessary wear and premature deterioration of the printing press.
In view of the above disclosure, it is the primary object of the invention to completely clean the surface of the web prior to entering a print unit, which considerably reduces blanket washing. It has been found that the invention can increase the number of impressions run before a blanket wash is required.
An important object of the invention is directed to condition high speed webs by penetrating the surface barrier of the web without actual contact. The invention produces an air flow that directs air currents in a turbulent washing film over the web surface, thus completely removing slitter dust, loose clay coating and other debris. The invention is designed to be completely functional with almost any substrate used in printing, without damage to its surface such as paper, mylar and plastic.
Another object of the invention is to apply the use of air currents that are produced by a roller with a textured surface. The roller creates a narrow, pressurized area immediately at an extremely close space existing between the roller and the web, which, due to such a limited sector develops immense energy to the web that dislodges debris and moves loose particles without touching the web. The roller may have any textured surface that will cause air movement above its surface, however it has been found by extensive testing that a roller similar in design to a jewelry polishing wheel which is constructed of soft cotton buffing material, has proven optimum. Once the contaminants are lifted from the surface of the web they may be easily directed to a separate device that receives and stores the debris. The roller works best when the roller""s surface speed is at least 20 percent greater than the surface speed of the web.
Still another object of the invention is that the rollers rotate in the opposite direction as the moving web this feature permits the air currents that surround the rotating roller to be easily directed into a plenum, which includes a air separating bar that separates the air containing particles that have been removed from the web from the roller and directs the airflow into the plenum and on into a dust collector under negative pressure.
Yet another object of the invention is that by having a clean web, print quality is enhanced and a consistent color is obtained. The conditioned web, as provided by the inventive web cleaner, reduces contamination in not only the ink train and dampers but also specifically the blankets of the printing equipment.
These and other objects and advantages of the present invention will become apparent from the subsequent detailed description of the preferred embodiment and the appended claims taken in conjunction with the accompanying drawings.